UVB overexposure from BULBS??

[anthony]

Ok. My 160 Watt self ballastered mercury vapor bulb is getting a little too hot for the weather here as summer approaches. Besides, its about a month or so away from when I had planned to replace it anyway, so I think I'm gonna head over to the store to buy bulbs.

I was thinking of either a 100 watt MVB, or TWO 60 watt MVBs. I would think that the two 60 watts would be better, as a 60 watt drop would be a little drastic as the temps are only a little above what they should be. However, I am hearing contradictory info on MVB UVB output.

Firstly, I am told that the UVB output of an MVB is INDEPENENT of the wattage. i.e., the same UVB output from a 60 watt, a 100 watt and 160 watt, just different electricity consumption and heat (correct me if I'm wrong).

Secondly, I was told by a knowledgeable friend that two 60 watt MVBs would be too much, possibly leading to UVB over exposure. Online care sheets say the same thing. HOWEVER, they are always also (sometimes on the same page) raving about how great direct sunlight is, and how 30 mins of sunlight is better than 12 hours of any bulb commercially available. They are not just referring to florescents either.

So, given that iguanas naturally bask in real sunlight, which supposedly gives off way more UVB than any bulb, how can two MVBs be too much?

[IguanaKing]

The UVB output being independent of wattage is not entirely true, the wattage is the total power dissipated by that lamp. How much of that power goes to what part of the light spectrum depends on the bulb and ballast design.

Also UVB levels from any source is dependent on distance between the animal and the UVB source. It IS possible to overexpose an iguana, but that's only when you get them too close...AND when you don't provide the animal with the means to seek shelter from the rays when his body tells him to. Some UVB bulbs are actually capable of producing several times what is found in nature if the bulb is too close. Its also important to remember that in the wild, an iguana generally only spends 20 to 30 minutes at a time basking in the sun, then they retreat to a shady spot to cool off. This cycle continues throughout the day.

With all that being said, however, the best advice I can give is that you purchase a UVB meter. I highly recommend the SolorMeter 6.2. Ideally you should read between 100-200uW in the basking spot, and provide an area in the cage in which the animal can seek shelter from the lamps when he needs to.

[Marie]

My recommendation would be get a meter too but I know it is harder to get the same products in China. So I'd go with just one of either the 60 or 100 and set it at the recommended distance for that bulb (unless you get other reliable information for the bulb). The recommended distance is based on the UVB output for the bulb. Then I would control the heat using another source such as an ordinary lightbulb or a CHE. In the future if you need more or less heat you won't need to change the MVB (unless it is time to).

[anthony]

Without a UVB meter, you think for the rep-pro bulbs changing them every 6 months say is within the safety margin?

[Marie]

I don't know much about that brand but know of some people who are testing them. When I can catch them I will definitely ask them. But I would hazard to guess that is a good replacement schedule.

[Iguana Momma]

Where can a meter be purchased? And is it expensive? Also, what should happen physically to an iguana when it is under a light that produces UVB as opposed to one that does not? (i.e. color change? behavior change? increased appetite?) -Just want to make sure mine are working correctly.

[Marie]

They are the Solarmeter 6.2. They range from $149-$179 plus s/h. You could also sign up for the next group buy at the Yahoo UVB Meter Owner's Group (don't need to actually own a meter to join). They were $130 shipping included if paid by check/money order or $140 shipping included if paid with PayPal the last time. I bought mine that way. Seems pricey but they end up paying for themselves. You save in not replacing bulbs that are still good. Also you save in vet bills that might result if you get a bad bulb. I have MegaRays that have gone past the 1 year replacement schedule since I can read the output. They are $149 + $11 s/h here market.kingsnake.com/detail.php?cat=22&de=230115 .

[prism_wolf]

empoyner said:

Seems pricey but they end up paying for themselves. You save in not replacing bulbs that are still good.

Especially when you have several reptiles that need UVB. I saved in the first year.

Also, what should happen physically to an iguana when it is under a light that produces UVB as opposed to one that does not? (i.e. color change? behavior change? increased appetite?)

Death...eventually. MBD (metabolic bone disease) is a result of no UVB (and bad diet and poor temps). They can eat like a horse with a good diet, temps can be perfect, but without the UVB to metabolize the vitamin D3 in their diet which aids in calcium absorption...the calcium is drawn from the ig's own bones making them brittle. It also reaks havock on the internal organs and many igs die from renal failure due to the MBD. Their color dulls quite noticeably. They are not as active without it. UVB means life for them... .

[Iguana Momma]

I guess what I am wondering is if there is a skin change color that should happen- like when you take them out into the sun they usually get darker... will that happen with the UVB bulbs?

Thanks guys!

[IguanaKing]

You may or may not notice a brightening of the colors, but much of that will depend on how healthy the animal is to begin with. If he's already in good health, you might not notice much change (of course, every ig is different though, so its difficult to say for sure)The color change you see when you take your ig outside is based more on how hot or cold your ig is.

[Merlin]

I agree you really can't count on the skin appearance to tell you whether your bulb is putting out UVB or not.
UVB light is invisible to our eyes and so would have no visible effect on color.